This invention relates to a document feeding apparatus which enables image reading by feeding an original document in order to form an image by an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile machine, a compound machine having these plural functions, or a printing machine, and to an image forming apparatus.
Some of document feeding apparatus provided in such an image forming apparatus of a digital type separate to feed a single sheet from the other document sheets stacked on the sheet feeding tray, and are capable of reading the both sides of the document by switching over the pathway between the ejecting passage and the reversing passage.
In such a document feeding apparatus, the reversing rollers and the ejecting rollers are arranged separately in the up-and-down direction, therefore, the document feeding apparatus is made large-sized in the height direction. Further, because the switching gate for switching over the pathway between the ejecting passage and the reversing passage is disposed at the upstream side of the reversing rollers and the ejecting rollers, the document feeding apparatus is made large-sized in the width direction.
In the reversing passage, a document sheet is conveyed in direct contact with the guide ribs forming the reversing passage, therefore, the resistance to conveyance is large, and the document sheet skews, often to cause a paper jam to occur.
Further, a pair of ejecting rollers for ejecting a document sheet after being read and an ejected sheet guide member for guiding the document sheet to be ejected are provided, but the ejecting rollers and the ejection guide members are mounted separately; therefore, the document feeding apparatus is made large-sized.
This invention has been made in view of the above-mentioned points; it is an object of the invention to provide a document feeding apparatus and an image forming apparatus, which make it possible to make its size smaller by employing a part for common use to plural members and reducing the number of parts, and also make it possible to raise the document conveying ability.
In order to solve the above-mentioned problems and to accomplish the object, this invention is made to have any one of the following structures.
An apparatus for feeding a both-sided document having images on both sides thereof, comprises:
a document stand on which the both-sided document is placed;
a reading section at which an image of the both-sided document is read by an image reader;
a feeder having a feeding passage and to feed the both-sided document from the document stand to the reading section along the feeding passage;
a pair of reversing rollers provided on a reversing passage to reverse the both-sided document after an image of the both-sided document is read at the reading section and to reefed the reversed both-sided document from the reversing passage to the feeding passage so that an image on another side of the both-sided document is read at the reading section;
a pair of ejecting rollers provided on an ejecting passage and to eject the both-sided document to a delivery section after the images on both sides of the both-sided document are read at the reading section; and
a switching mechanism to connect an outlet passage of the reading section to one of the reversing passage and the ejecting passage;
wherein one of the pair of reversing rollers and one of the ejecting rollers are mounted coaxially on a shaft.
An image forming apparatus, comprises:
an image reader to read an image on a document;
a recording device to record an image on a recording sheet based on the image read by the image reader; and
a document conveying device to convey a both-sided document to the image reader in such a way that images on the both-sided document are read by the image reader,
the document conveying device comprising
a document stand on which the both-sided document is placed;
a reading section at which an image of the both-sided document is read by the image reader;
a feeder having a feeding passage and to feed the both-sided document from the document stand to the reading section along the feeding passage;
a pair of reversing rollers provided on a reversing passage to reverse the both-sided document after an image of the both-sided document is read at the reading section and to reefed the reversed both-sided document from the reversing passage to the feeding passage so that an image on another side of the both-sided document is read at the reading section;
a pair of ejecting rollers provided on an ejecting passage and to eject the both-sided document to a delivery section after the images on both sides of the both-sided document are read at the reading section; and
a switching mechanism to connect an outlet passage of the reading section to one of the reversing passage and the ejecting passage;
wherein one of the pair of reversing rollers and one of the ejecting rollers are mounted coaxially on a shaft.
Further, the above object may be attained by the following preferable structures.
(1) A document feeding apparatus, which separates to feed a single sheet from the other document sheets stacked on a sheet feeding tray (document stand) and are capable of reading the both sides of a document sheet, comprising
a document reading section arranged in the lower part and a reversing passage and a pair of reversing rollers for reading the both sides of the document sheet arranged in the upper part,
an ejecting passage and a pair of ejecting rollers arranged at the downstream side of said document reading section, and
a switching gate for switching over the pathway from said document reading section between said reversing passage and said ejecting passage, wherein
the driven one of said pair of reversing rollers and the driving one of said pair of ejecting rollers are arranged on the same shaft.
According to the invention described in the structure (1), the driven one of the pair of reversing rollers and the driving one of the pair of ejecting rollers are disposed on the same shaft; therefore, the number of parts is made smaller, and it is possible to make the size in the height direction smaller.
(2) A document feeding apparatus as set forth in the structure (1), wherein the supporting point (fulcrum) of the aforesaid switching gate is provided on the aforesaid shaft.
According to the invention described in the structure (2), the supporting point of the switching gate is provided on the shaft on which the driven one of the pair of reversing rollers and the driving one of the pair of ejecting rollers are provided; therefore, the number of parts is made smaller, and it is possible to make smaller the size in the width direction, on top of the height direction.
(3) A document feeding apparatus, which separates to feed a single sheet from the other document sheets stacked on a sheet feeding tray, is provided with a reversing passage for reading the both sides of a document sheet, and are capable of reading the both sides of the document sheet, wherein
a conveyance-resistance reducing rolling bar for reducing the resistance to conveyance of a document sheet is attached in said reversing passage.
According to the invention described in the structure (3), the resistance to conveyance of a document sheet in the reversing passage can be reduced by the conveyance-resistance reducing rolling bar; therefore, the conveying ability for a document is improved, and it becomes possible to reduce the frequency of the occurrence of a paper jam.
(4) A document feeding apparatus as set forth in the structure (3), wherein the aforesaid reversing passage bends in the shape of S, and at least in a part of the bending portions (curved bent portions), the aforesaid conveyance-resistance reducing rolling bar is disposed.
According to the invention described in the structure (4), the reversing passage is s-shaped, and the conveyance-resistance reducing rolling bar is disposed in the bending portion; therefore, the apparatus is made compact, and the document conveying ability in the bending portion is improved, to make it possible to reduce the frequency of the occurrence of a paper jam.
(5) A document feeding apparatus as set forth in the structure (3) or (4), wherein a plurality of the aforesaid conveyance-resistance reducing rolling bars are provided between the guide ribs forming the aforesaid reversing passage.
According to the invention described in the structure (5), a plurality of the aforesaid conveyance-resistance reducing rolling bars are provided between the guide ribs forming the aforesaid reversing passage; therefore, the apparatus is made compact, and the document conveying ability is improved, to make it possible to reduce the frequency of the occurrence of a paper jam.
(6) A document feeding apparatus as set forth in any one of the structures (3) to (5), wherein the aforesaid conveyance-resistance reducing rolling bar is provided in such a way that only a part of it is projected out of the aforesaid guide ribs toward the reversing passage in order that a document sheet may hit a portion of the rolling bar deviated to the sheet passing side from the central line.
According to the invention described in the structure (6), the conveyance-resistance reducing rolling bar is provided in such a way that only a part of it is projected out of the guide ribs toward the reversing passage side and a document sheet hits a portion of the rolling bar deviated to the sheet passing side from the central line; therefore, the apparatus is made compact, and the document conveying ability is improved.
(7) A document feeding apparatus, which separates to feed a single sheet from the other document sheets stacked on a sheet feeding tray and are capable of reading the both sides of a document sheet, comprising
a pair of outlet rollers for ejecting said document sheet after said document sheet is read and an outlet guide member for guiding a document sheet to be ejected, wherein
the shaft of one of said pair of outlet rollers is used also as the mounting portion for said outlet guide member.
According to the invention described in the structure (7), the shaft of one of the pair of outlet rollers is used also as the mounting portion for the outlet guide member; therefore, the number of parts is made smaller, and it is possible to make the size smaller.
(8) A document feeding apparatus as set forth in the structure (7), wherein the driving one and the driven one of the aforesaid pair of outlet rollers are pressed to each other by a ring-shaped spring.
According to the invention described in the structure (8), the driving one and the driven one of the aforesaid pair of outlet rollers are pressed to each other by a ring-shaped spring; therefore, the pair of ejecting rollers are made to form a compact unit.
(9) An image forming apparatus provided with a document feeding apparatus as set forth in any one of the structures (1) to (8).
According to the invention described in the structure (9), the image forming apparatus can be provided with a document feeding apparatus, which makes it possible to make its size smaller by employing a part for common use to plural members and reducing the number of parts, and also make it possible to raise the document conveying ability.